1) Place tomatoes, cucumber, bell pepper, onion, garlic, jalapeño, kale, lemon juice and salt into the pitcher of a blender or food processor and blend until smooth.
2) Chill for 2 hours and then blend again as liquid will separate some. To serve as soup, pour into bowls and top with chopped avocado and sliced green onions. Or just drink it like a smoothie!
Turns a brownish green that looks a bit like swamp muck, hence the name.